package com.study_security.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;


import java.time.LocalDateTime;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

@Slf4j
@Component
public class CacheClient {
    @Autowired
    private StringRedisTemplate stringRedisTemplate;
    public void set(String key, Object value, Long time, TimeUnit timeUnit)
    {
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value),time,timeUnit);
    }
    public void setWithLogicalExpire(String key, Object value, Long time, TimeUnit timeUnit)
    {
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(timeUnit.toSeconds(time)));
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
    }

    public <R, ID> R queryWithPassThrough(String keyPreFix, ID id, Class<R> type,
                                          Function<ID, R> dbFallback, Long time, TimeUnit timeUnit,
                                          Class<?> elementType) {
        String key = keyPreFix + id;
        String json = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isNotBlank(json)) {
            System.out.println("Cache hit");
            if (type.equals(List.class)) {
                return (R) JSONUtil.toList(JSONUtil.parseArray(json), elementType);
            } else {
                return JSONUtil.toBean(json, type);
            }
        }
        if (json != null) {
            System.out.println("Cache hit with null");
            return null;
        }
        R r = dbFallback.apply(id);
        if (r == null) {
            stringRedisTemplate.opsForValue().set(key, "", 2L, TimeUnit.MINUTES);
            return null;
        }
        this.set(key, r, time, timeUnit);
        return r;
    }

    private static final ExecutorService CACHE_REBUILD_EXECUTOR= Executors.newFixedThreadPool(10);
    public <R,ID> R queryWithLogicalExpire(String keyPreFix,ID id,Class<R> type,Function<ID,R> dbFallback,
                                           Long time, TimeUnit timeUnit)
    {
        String key=keyPreFix+id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isBlank(shopJson)) {

            return null;
        }
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        JSONObject data = (JSONObject)redisData.getData();
        R r = JSONUtil.toBean(data, type);
        LocalDateTime expireTime = redisData.getExpireTime();
        if (expireTime.isAfter(LocalDateTime.now()))
        {
            return r;
        }
        String lockKey="lock:shop:"+id;
        boolean b = tryLock(lockKey);
        if (b)
        {
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    //查询数据库
                    R apply = dbFallback.apply(id);

                    this.setWithLogicalExpire(key,apply,time,timeUnit);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    unLock(lockKey);
                }

            });
        }


        return r;
    }
    private boolean tryLock(String key)
    {
        Boolean b = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(b);
    }

    private void unLock(String key)
    {
        stringRedisTemplate.delete(key);
    }
}
